What is your OS?
What version of dreamweaver?
When installing the extension, you should open the extension first, then click the install button and browse to the extension file to start the installation.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.